<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div id="wrap">
        <h2>哈哈哈哈</h2>
        <ul class="list" title="">
            <li>01</li>
            <li>02</li>
            <li>03</li>
            <li>04</li>
        </ul>
        <ul class="list" title="">
            <li>01</li>
            <li>02</li>
            <li>03</li>
            <li>04</li>
        </ul>
    </div>
    <form action="">
        <p>
            <label for="">用户名:</label>
            <input type="text" name="user">
        </p>
        <p>
            <label for="">密&emsp;码:</label>
            <input type="text" name="pwd">
        </p>
        <p>
            <label for="">爱&emsp;好:</label>
            <input type="radio" name="hobby" value="sing">
            <input type="radio" name="hobby" value="dance">
            <input type="radio" name="hobby" value="play">
        </p>
    </form>
</body>
<script>
    //js组成
    // ECMAScript  => ES5(ES6)
    // BOM(Brower )
    // DOM()

    var wrap = document.getElementById("wrap");
    var list = document.getElementsByClassName("list")[0];
    console.log(wrap);
    console.log(list);
    var a = list.getElementsByTagNameNS(小广告.html , tagName)//两个参数：第一个是本网页之外的第二个网页名，第二个是标签名
</script>
</html>